JPH0617574B2 - Construction method of impermeable wall - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method of constructing an impermeable wall, which has a particularly high water-stopping ability and can maintain sufficient water-stopping property even if a crack occurs due to an earthquake or the like. Moreover, the present invention relates to a method of constructing an impermeable wall that has an ability to adsorb dissolved substances in water.

<< Prior Art >> As is well known, the impermeable walls include concrete continuous walls, impermeable walls made of a self-hardening stabilizer, and soil mortar column walls.

All of these impermeable walls are impermeable walls made of a cement mixture, and all have a low water permeability, are superior in impermeable performance, and have sufficient strength and rigidity.

<Problems to be Solved by the Invention> However, the permeability coefficient of any of these impermeable walls is limited to 10 ⁻⁶ to 10 ⁻⁸ cm / Sec, and an impermeable wall having high water blocking property is obtained. There was a problem that could not be dealt with when trying to do so.

In addition, these water-impervious walls have a poor ability to follow the natural ground, and have a drawback that when an earthquake or the like occurs, cracks occur and the water-stopping property decreases.

Further, the impermeable wall made of these cement mixture materials does not have a function of adsorbing and retaining the polluted dissolved substances in water. Therefore, once cracks occur, it is not possible to prevent the diffusion of these dissolved substances in water to the outside,
Its use as a barrier for purifying pollutants dissolved in groundwater was limited.

The present invention solves the above problems and has a higher water blocking capacity than the conventional water blocking wall, and maintains sufficient water blocking capability even if a crack occurs due to an earthquake or the like. It is an object of the present invention to provide a method of constructing an impermeable wall, which is capable of adsorbing dissolved substances in water.

<< Means for Solving the Problems >> In order to achieve the above-mentioned object, the present invention forms a drilling hole while filling mud in which clay such as bentonite is suspended, and replaces the mud with a cement mixture in order. In the method of constructing a water-impervious wall in which a continuous wall is constructed, a positive electrode member having a three-dimensional mesh shape is installed substantially at the center in the width direction of the drilled hole after the drilled hole is formed, and the negative electrode is opposed to the positive electrode member. Members are arranged, a DC power source is connected between these electrode members, a water blocking film layer made of the clay is formed on the positive electrode member side, and then the cement mixture is cast into the drill hole. Characterize.

<< Operation >> According to the above configuration, when a DC voltage is applied between the positive electrode member and the negative electrode member, clay particles such as bentonite move to the positive electrode member side due to the electroosmosis phenomenon and the electrophoretic phenomenon and accumulate there. Then, a water blocking film in which clay particles are concentrated to a high concentration is formed.

Therefore, when the cement mixture is subsequently cast to construct the water blocking wall, a flexible water blocking film layer in which clay particles are accumulated on the positive electrode member having a three-dimensional network is formed in a part thereof.

This water stop film layer does not crack even if a crack occurs on the external water shield wall, and can maintain water impermeability.
Further, since the water-stop film layer is a high concentration of clay particles, the surface area of each particle is large and it has the ability to adsorb dissolved substances in water.

<< Embodiment >> An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a first embodiment of the present invention.

In the response report for the construction of the impermeable wall shown in Fig. 1, first, Fig. 1 (a)
A rectangular groove-shaped drill hole 10 is formed by drilling as shown in FIG.

The excavation of the excavation hole 10 is performed by filling the mud 12 in which clay such as bentonite is suspended inside the excavation hole 10 while preventing the collapse of the excavation hole wall, and constructing an impermeable wall. It will be drilled to the planned depth.

When the drill hole 10 is formed, as shown in FIG. 1 (b), the three-dimensional mesh positive electrode member 14 is installed along the longitudinal direction of the drill hole 10 at a substantially central position in the width direction thereof.
A plurality of electrode rods 16 as negative electrode members are arranged along both hole walls 10 a so as to face the positive electrode member 14. The electrode rod 16 may be arranged only on one hole wall 10a.

As the material of the three-dimensional mesh positive electrode member 14, any material having conductivity can be used. For example, a wire mesh or the like having a predetermined thickness, a carbon fiber mesh or the like is used, and its specific resistance value is 10 ^{−. 3} Ωm or less is suitable, and it is braided with a predetermined thickness with respect to the width of the drill hole 10.

In addition to bentonite, clay such as zeolite may be added to the muddy water 12, and more preferably, a clay substance having an ion adsorbing property may be added.

Then, in a state where the positive electrode member 14 and the electrode rod 16 are installed facing each other at a predetermined position, the positive electrode member 14 has a DC power supply 18
Of the electrode rods 16 are connected to each other via the lead wire 20.
Are connected in series to the negative electrode side of the DC power supply 18 via lead wires 22.

As a result, an electric field corresponding to the voltage of the DC power supply 18 is formed between the positive electrode member 14 and the electrode rod 16, and the muddy water 12
Will be present in this electric field.

When the muddy water 12 exists in the electric field, clay particles such as bentonite in the muddy water 12 move to the positive electrode side, that is, the positive electrode member 14 side due to the electrophoretic phenomenon, and the water in the muddy water moves to the electrode rod 1.
Move to side 6.

Then, when the direct current voltage is continuously applied between the positive electrode member 14 and the electrode rod 16, the clay particles adhere to the surface of the positive electrode member 14 and gradually accumulate, and as shown in FIG. A water blocking film layer 24 having a predetermined thickness and having a high concentration is formed on the periphery of the positive electrode member 14.

In this case, the voltage of the DC power supply 18 is in the range of 1 to 50V.

When the water blocking film layer 24 is formed to have a predetermined thickness, FIG.
As shown in FIG. 5, the cement mixture 26 is placed in the drill hole 10 to replace the muddy water with the cement mixture 26. A panel-shaped wall body is constructed by hardening the cement mixture 26 that has been cast, and thereafter, by repeating the above steps in sequence, a water-impervious wall having a predetermined length is formed by laterally connecting the panel-shaped wall bodies. .

When the cement mixture is poured, the water blocking film layer 24 can be made solid with the clay particles by the casting pressure of the cement mixture 26.

The impermeable wall formed as described above is formed in a state in which the waterproof membrane layer 24 is wrapped inside the impermeable wall made of the cement mixture 26, so that the permeability coefficient of the impermeable wall is considerably small. Can be one.

According to the experiments conducted by the present inventors, it has been confirmed that in the case where the water blocking film layer 24 has bentonite accumulated, a hydraulic conductivity of 10 ⁻⁸ to 10 ⁻¹⁰ cm / Sec or less can be obtained.

In addition, in the impermeable wall having the waterproof membrane layer 24 wrapped therein as described above, even if the hardened material of the cement mixture 26, which is the main portion of the impermeable wall, is cracked by an earthquake or the like after construction, The water blocking film layer 24 has a plastic property, and follows the deformation of the surroundings well to prevent cracking. Therefore, in addition to ensuring the waterproofness after cracks occur,
The water-stopping film layer 24 itself has an adsorbing ability to adsorb a pollutant dissolved substance in water, so that the diffusion of the pollutant can be prevented.

Next, FIG. 2 shows a second embodiment of the present invention.
As shown in FIG. 1A, the three-dimensional net-like positive electrode members 14 are arranged in parallel in the width direction of the excavation hole 10 in two rows at approximately the center position in the width direction, and the electrode rods 1 arranged on the respective hole walls 10a.
6 and the clay particles are accumulated on the surface of each positive electrode member 14.

Therefore, in this example, the obtained water blocking wall has two rows of the water blocking membrane layers 24 inside the cement mixture 26 to further improve the water blocking ability, and at the same time the water blocking and dissolution in water at the time of crack occurrence. It is designed to improve its ability to adsorb substances.

In addition, although the case where the cement mixture 26 is filled on both sides of the waterproof membrane layer 24 is illustrated in the above embodiment, the waterproof membrane layer 24 is illustrated.
May be brought into close contact with one wall surface side of the drill hole 10 and the cement mixture 26 may be filled in only one side.

<< Effects of the Invention >> As described in detail above with reference to the embodiments, the method of constructing the impermeable wall according to the present invention has the following advantages.

Compared with the conventional impermeable walls made of cement mixture alone, the coefficient of water permeability becomes smaller, and the water blocking performance can be further improved.

Even if the cement mixture, which is the main body of the water blocking wall, is cracked by an external force such as an earthquake, the water blocking membrane layer inside can keep the water blocking property.

Since the water-blocking film layer has the ability to adsorb pollutant dissolved substances in water, it is possible to prevent the diffusion of these substances.

[Brief description of drawings]

1 (a) to 1 (d) are plan views for explaining the first embodiment of the present invention in the order of steps, and FIGS. 2 (a) and 2 (b) are plan views for explaining the second embodiment of the present invention. It is a figure. 10 ... Drilled hole, 12 ... Mud, 14 ... Positive electrode member, 16 ... Electrode rod, 18 ... DC power supply, 24 ... Water-stop film layer, 26 ... Cement mixture

Claims (1)

[Claims] 1. A method of constructing an impermeable wall in which a drill hole is formed while filling mud in which clay such as bentonite is suspended, and the mud is replaced with a cement mixture to successively construct a continuous wall in the ground. After forming the excavation hole, a three-dimensional mesh positive electrode member is installed substantially at the center of the width of the excavation hole, a negative electrode member is arranged facing the positive electrode member, and a DC power source is connected between these electrode members. Then, a water blocking film layer made of the clay is formed on the positive electrode member side, and then the cement mixture is placed in the excavation hole, which is a method of constructing a water blocking wall.